Project Summary/Abstract The primary aim of the current R01 application is to examine the efficacy and maintenance of a home-based preventive intervention to decrease behavior problems in infants from high-risk families. Behavior problems are exceedingly common in early childhood and are associated with high impairment and a long-term negative trajectory for negative outcomes. Despite the empirical evidence supporting the use of clinic-based parent- training treatments for early behavior problems, children from economically disadvantaged and underrepresented minority families, who are at considerably higher risk for behavior problems, have higher treatment dropout rates and poorer outcomes when completing treatment. We propose instead to intervene during infancy, which would likely require less intensive and shorter interventions, thereby decreasing the burden for high-risk families. Extending promising findings from pilot testing of a home-based intervention targeting changes in parenting behavior (K23 MH085659: PI, Bagner), we propose to conduct an adequately powered randomized controlled trial (n = 288) to demonstrate its efficacy and maintenance in reducing behavior problems and increasing infant regulation relative to an enhanced pediatric primary care active control condition. Based on work by the current investigative team and others, we also will examine the mediating role of changes in parenting behavior and the moderating role of parental distress on intervention outcome. Rather than focus exclusively on whether the effect of the intervention can be produced, an important step in further developing the evidence base in prevention science is to examine how and for whom indicated preventive interventions work. The proposed work is consistent with the research priorities of the Child Development and Behavior Branch (CDBB) of the NICHD to investigate the impact of a behavioral promotion intervention in pediatric primary care and identify developmental factors and mechanisms which promote short- and long-term psychosocial adjustment for children exposed to high-risk family and neighborhood environments. In light of the extensive needs and depleting resources faced by low-income and underrepresented minority families, the proposed work provides a unique opportunity to help promote optimal behavioral functioning and reduce the risk for psychopathology in infants from the most vulnerable families.